1. Field of Invention
The present invention relates to a liquid crystal display device, and more particularly, it relates to a liquid crystal display device with a wide viewing angle.
2. Related Art
The liquid crystal display device adjusts liquid crystal orientations to control a transmission of light beam, and this disturbs the device from providing a sufficient range of a viewing angle to obtain a satisfactory display.
For example, Patent Document 1 listed below discloses a mode suitable to obtain a sufficient viewing angle. In this mode, called “Vertical Alignment (VA)” mode, molecules of liquid crystal align themselves to make vertical chains without applying voltage, and they align in horizontal chains when voltage is applied. The cited document teaches that a varied direction of observing alters a retardation (optical length) to equally vary a resultantly displayed image depending upon a visual direction of the viewer. When dependency of the retardation upon the viewing angle increases, allowable viewing angle concomitant with a deteriorated visibility of a display panel is accordingly degraded.
In order to overcome the aforementioned issue of interest on the allowable viewing angle, Patent Document 1 proposes a stacked structure. In the stacked structure, some optical components such as polarizing plates and wavelength plates underlie and overlie a liquid crystal layer. Specifically, in the cited document, a transmissive liquid crystal display device is described in conjunction with a schematic sectional view of FIG. 6. FIG. 6 depicts an exemplary stacked arrangement with a polarizing plate (on the observer side) 1, a λ/2 retardation plate 2, a λ/4 retardation plate 3, a liquid crystal layer 4, a λ/4 retardation plate 5, a λ/2 retardation plate 6, and a polarizing plate (on the backlight side) 7. The liquid crystal layer 4 has orientating layers 4a and 4b on its opposed major surfaces. The polarizing plate 7 is laid one over another in the top-down order. In such an arrangement, two of the λ/2 retardation plates, being vertically symmetrical about the liquid crystal layer, have respective retardation axes which are shifted 90 degrees from each other and out of phase. Another pair of the λ/4 retardation plates are disposed similarly.